possible battery problems

worried_jim

Typical. It works fine all day yesterday and this morning nothing. A day off work and a bill. Don't you just love Mondays.

A friend with a volt metre has just checked the battery. 12v. cleaned up the connections with some wd40 and gave it a push, started straight away.Popped the bonnet again and it was reading 13.5v with the engine running. Have driven to the local independent who I've been using for years and now sitting by the phone.

Premier_2

worried_jim wrote: »

Typical. It works fine all day yesterday and this morning nothing. A day off work and a bill. Don't you just love Mondays.

A friend with a volt metre has just checked the battery. 12v. cleaned up the connections with some wd40 and gave it a push, started straight away.Popped the bonnet again and it was reading 13.5v with the engine running. Have driven to the local independent who I've been using for years and now sitting by the phone.

Taking voltage readings only tells you the battery is not discharged.

(with engine running, it tells you the voltage the alternator is outputting)

What you need is a load test on the battery without the engine running. Takes literally less than a couple of minutes.

Chippy_Minton_2

What did you give it for Sunday dinner?

worried_jim

Just had a new alternator fitted (£133), everything should be fine now. Won't be able to afford another Sunday dinner for a while.

goldspanners

worried_jim wrote: »

12v. cleaned up the connections with some wd40 and gave it a push, started straight away.Popped the bonnet again and it was reading 13.5v with the engine running.

worried_jim wrote: »

Just had a new alternator fitted (£133), everything should be fine now.

i don't know if i would be too sure jim, if you were getting 13.5 volts when the engine was running then the alternator was working. if the alternator was failing you could have expected to see the charging light coming on on your dashboard while driving it.

Wig

You should test with the engine running = 13.5v = ok but then should test again with the headlights on and the rear demister on, might also put the front window motors on aswell, you should still get 13.5 volts.

If you'd done that and it was still 13.5v there was no need for a new alternator. But as you didn't do that you'll never know.

molerat

13.5 is a bit low for Vauxhall, usually just over 14. If a diode was dodgy the alternator could be charging but as soon as shut down it would discharge. My car passed the simple voltmeter checks but the diode pack was faulty, which I suspected, but was confirmed by a proper test.

mikey72

Wig wrote: »

You should test with the engine running = 13.5v = ok but then should test again with the headlights on and the rear demister on, might also put the front window motors on aswell, you should still get 13.5 volts.

If you'd done that and it was still 13.5v there was no need for a new alternator. But as you didn't do that you'll never know.

Yes he will, it'll either start, or it won't again.

Wig

molerat wrote: »

13.5 is a bit low for Vauxhall, usually just over 14. If a diode was dodgy the alternator could be charging but as soon as shut down it would discharge. My car passed the simple voltmeter checks but the diode pack was faulty, which I suspected, but was confirmed by a proper test.

AFAIK you can't do "a proper test" all you can do with an alternator is voltmeter check. And it doesn't tell you what part of the alternator is faulty you just know it is faulty, can be regulator, windings (unlikely) or the diodes. Usually you replace the regulator and if it doesn't fix it you know it is the diodes.

Happy to be corrected, but even if there was some fancy oscilliscope test that can be done I doubt many places have the equipment to do it.

My Corsa is 13.4 - 13.5 V

worried_jim

Well I suppose the moment of truth will come tomorrow morning at 8.15. I was feeling pretty confident if not a whole lot poorer until I read these latest comments.